Boot Configuration Control via Expansion Bus
8-49
Expansion Bus
8.7
Boot Configuration Control via Expansion Bus
The polarity of read/write XW/R and XBLAST control signals on the expansion
bus is determined during boot using pull up/pull down resistors on the XD[31:0]
pins of the expansion bus. Pull up/pull down resistors on the expansion bus
are used for boot mode selection and to enable/disable internal bus arbiter, to
define expansion bus host port mode to define memory type used in each
expansion bus memory space and to define FIFO mode. All expansion data
pins, XD[31:0], should be configured by pull-up/pull-down resistors. Reserved
fields should be pulled-down. Detailed description of boot configuration is
shown in Figure 8–28 and Table 8–20.
Figure 8–28. Expansion Bus Boot Configuration via Pull Up/Pull Down Resistors on
XD[31:0]
31
30
29
28
27
26
25
24
23
22
20
19
18
16
rsvd
MTYPE XCE3
rsvd
MTYPE XCE2
rsvd
MTYPE XCE1
rsvd
MTYPE XCE0
15
14
13
12
11
10
9
8
7
5
4
0
Reserved
BLPOL
RWPOL
HMOD
XARB
FMOD
LEND
Reserved
BOOTMODE